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Date:   Mon, 28 Mar 2022 12:57:20 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org,
        linux-next@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH] mm/munlock: remove fields to fix htmldocs warnings
Message-ID: <d2c8f66d-be8e-7c91-b0c8-b2f7ffb08bec@google.com>
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Stephen reports that 'make htmldocs' currently issues two warnings:
include/linux/mm_types.h:275: warning: Function parameter or member
'__filler' not described in 'folio'
include/linux/mm_types.h:275: warning: Function parameter or member
'mlock_count' not described in 'folio'

Certainly __filler doesn't want documenting there, and all but one use of
mlock_count is through page->mlock_count at present: so I think it's best
just to remove them both from struct folio for now, and sort out the
right way to document folio->mlock_count once that is the one true way.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 07ca76067308 ("mm/munlock: maintain page->mlock_count while unevictable")
Signed-off-by: Hugh Dickins <hughd@google.com>
---

 include/linux/mm_types.h |    8 +-------
 mm/swap.c                |    4 ++--
 2 files changed, 3 insertions(+), 9 deletions(-)

--- 5.18-pre/include/linux/mm_types.h
+++ linux/include/linux/mm_types.h
@@ -253,13 +253,7 @@ struct folio {
 		struct {
 	/* public: */
 			unsigned long flags;
-			union {
-				struct list_head lru;
-				struct {
-					void *__filler;
-					unsigned int mlock_count;
-				};
-			};
+			struct list_head lru;
 			struct address_space *mapping;
 			pgoff_t index;
 			void *private;
--- 5.18-pre/mm/swap.c
+++ linux/mm/swap.c
@@ -1026,13 +1026,13 @@ static void __pagevec_lru_add_fn(struct
 		folio_clear_active(folio);
 		folio_set_unevictable(folio);
 		/*
-		 * folio->mlock_count = !!folio_test_mlocked(folio)?
+		 * page->mlock_count = !!PageMlocked(page)?
 		 * But that leaves __mlock_page() in doubt whether another
 		 * actor has already counted the mlock or not.  Err on the
 		 * safe side, underestimate, let page reclaim fix it, rather
 		 * than leaving a page on the unevictable LRU indefinitely.
 		 */
-		folio->mlock_count = 0;
+		folio_page(folio, 0)->mlock_count = 0;
 		if (!was_unevictable)
 			__count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
 	}